面向应力对GaN晶格热导率的影响研究

Effects of In-plane Strain on Lattice Thermal Conductivity of GaN

本文针对GaN基电子器件散热的背景,基于第一性原理计算方法,系统研究了氮化镓的声子性质和晶格热导率以及面向应力对这些性质的影响。计算表明,面向应力会造成热导率的显著变化,在+5%拉应力下室温热导率降低63%,在-5%压应力下室温热导率增加53%。同时应力造成了热导率各向异性的改变,自由状态下室温热导率的各向异性较弱,由于应力对群速度作用的各向异性,拉应力下法向热导率显著高于面向热导率,压应力下则相反。

Thermal management in GaN based power electronic devices is now becoming a big challenge.In this work,phonon properties and lattice thermal conductivity of GaN and effects of in-plane strain on them are systematically investigated by first principle calculation method.The results show that in-plane strain makes a difference to lattice thermal conductivity,i.e.decreases lattice thermal conductivity at room temperature by 63%at+5%tensile strain condition while increases that by 53%at-5%compressive strain condition.Besides,in-plane strain induces the change of anisotropy of lattice thermal conductivity,as the anisotropy at free state is weak.Detailed phonon analyses indicate that the change of anisotropy results from the different effects of in-plane strain on in-plane and cross plane lattice thermal conductivity.